Projection system for displaying at least one image based on three filtered primary colours

• US 8,172,402 B2
• Filed: 02/20/2008
• Issued: 05/08/2012
• Est. Priority Date: 03/05/2007
• Status: Expired due to Fees

• Current Assignee: Magnolia Licensing LLC (IP Edge LLC)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Vigouroux, Jean-Ronan, Bourdon, Pascal, Doyen, Didier, Sacre, Jean-Jacques, Morvan, Patrick, Thiebaud, Sylvain
• Primary Examiner(s): Epps, Georgia Y
• Assistant Examiner(s): Cruz, Magda
• Application Number:
  US12/449,934
• Publication Number:
  US 20100085491A1
• Time in Patent Office: 1,539 Days
• Field of Search: 353/30, 353/31, 353/94, 348/757, 348/835, 345/604, 345/589, 345/204, 345/32
• US Class Current: 353/31
• CPC Class Codes: H04N 2005/9135 by superimposing the spectrally spread copy protection signal onto the video signal
• CPC Class Codes: H04N 2005/91392 using means for preventing making copies of projected video images
• CPC Class Codes: H04N 5/913 for scrambling ; for copy protection

Abstract

The invention relates to a projection system for displaying at least one visual image based on three primary colors, comprising a signal processing unit for converting said visual image into at least a visual image based on four primary colors, a frequency band being associated to each color primary, first display means for displaying three first primary colors of said visual image on a screen and second display means for displaying at least the fourth primary color of said visual image on said screen. According to the invention, the system further comprises optical filtering means that are adapted to enhance the separation between the frequency spectrum of the first three primary colors of the first display means and the frequency spectrum of the at least fourth primary color of the second display means. Application to anti-camcorder systems.

Claims

1. A projection system for displaying at least one visual image based on three primary colours, said projection system comprising:

a signal processing unit for converting said visual image into a visual image based on at least four primary colours, a frequency spectrum being associated to each primary colour;

first display means for displaying three first primary colours of said converted visual image on a screen, said three first primary colours being respectively red, green and blue;

second display means for displaying at least a fourth primary colour of said converted visual image on said screen; and

optical filtering means that are located between said first and or second display means and said screen and that are adapted to enhance the separation between the frequency spectrum of the three first primary colours of the first display means and the frequency spectrum of the at least fourth primary colour of the second display means, wherein said optical filtering means comprises a notch filter located between said first display means and the screen to attenuate or block at least a portion of the frequencies of at least one of the three first primary colours in the frequency spectrum associated to the fourth primary colour.

2. The projection system according to claim 1 wherein, in a CIE xy chromaticity space and under a D65 or a C illuminant, if x_R, y_R are the coordinates of the red primary colour of the three first primary colours, if x_G, y_G are the coordinates of the green primary colour of the three first primary colours, if x_B, y_B are the coordinates of the blue primary colour of the three first primary colours, then, x_R≧

0.63 and y_R≧

0.34, x_G≦

0.31 and y_G≧

0.59, x_B≧

0.14 and y_B≦

0.08.

3. The projection system according to claim 1, wherein said fourth primary colour of the second display means has a red colour with a frequency spectrum developing more luminous power in the range of large wavelengths that the frequency spectrum of the red primary colour of the first display means.

4. The projection system according to claim 1, wherein, in a CIE xy chromaticity space and under a D65 or a C illuminant, if x_R0, y_R0 are the coordinates of the red primary colour of the three first primary colours, if x_Rn, y_Rn are the coordinates of the said fourth primary colour, then x_Rn≧

x_R0 and y_Rn≦

y_R0.

5. The projection system according to claim 1, wherein, the notch filter blocks, in the frequency spectrum associated to the fourth primary colour, frequencies of two of the three first primary colours.

6. The projection system according to claim 1, wherein said optical filtering means further comprises a band-pass filter located between said second display means and the screen to reduce the frequency spectrum of the fourth primary colour.

7. Use of the projection system according to claim 1 to generate two different spectral power distributions for a given visual colour in a picture displayed by said projection system.

8. A display system, comprising:

means for converting a visual image based on three primary colours into a visual image based on at least four primary colours, wherein a frequency spectrum is associated with each of said primary colours;

first means for enabling display of three first primary colours of said converted visual image on a screen, said three first primary colours being respectively red, green and blue;

second means for enabling display of at least a fourth primary colour of said converted visual image on said screen; and

a notch filter positioned between said first display enabling means and said screen to attenuate or block at least a portion of the frequencies of at least one of said three first primary colours in the frequency spectrum associated with said fourth primary colour.

9. A method, comprising:

converting a visual image based on three primary colours into a visual image based on at least four primary colours, wherein a frequency spectrum is associated with each of said primary colours;

enabling display of three first primary colours of said converted visual image on a screen, said three first primary colours being respectively red, green and blue;

enabling display of at least a fourth primary colour of said converted visual image on said screen; and

providing a notch filter between means for enabling display of said three first primary colours and said screen to attenuate or block at least a portion of the frequencies of at least one of said three first primary colours in the frequency spectrum associated with said fourth primary colour.